Apparatus and method of sensing liquid leakage for lithography apparatus

CROSS-REFERENCE TO RELATED APPLICATION

0001This application claims priority from Korean Patent Application No. 10-2014-0167105 filed on Nov. 27, 2014 in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. 119, the contents of which in its entirety are herein incorporated by reference.

FIELD

0002The present inventive concept relates to an apparatus and method of sensing liquid leakage for a lithography apparatus.

BACKGROUND

0003Recently, in order to achieve micro-fabrication of semiconductor devices, a lithography process using extreme ultra violet (EUV) radiation has been proposed. In the lithographic process, light, also referred to as a light beam, may be projected on a silicon substrate through a mask having a circuit pattern, thereby forming an electronic circuit by exposing a photoresist material.

0004The minimal processing dimensions of the circuit formed by optical lithography are generally dependent on the wavelength of the light source. Accordingly, in order to produce circuitry having smaller geometries, a shorter wavelength of light may be used in a light source used for a photo-lithographic process. As a next-generation lithography light source, a EUV light source is suitably used. Extreme ultraviolet (EUV) radiation has a wavelength of from approximately 1 to 100 nm. Since light within this range has high absorptivity with respect to many materials, a transmissive optical system, such as a lens, may not be used but a reflective optical system may be used.

0005In order to generate EUV radiation, laser produced plasma (LPP) and discharge produced plasma (DPP) driven by pulse power technology may be used.

SUMMARY

0006The present inventive concept provides a liquid leakage sensing apparatus, which can prevent a collector mirror from being contaminated by sensing leakage of cooling water supplied to the collector mirror of an extreme ultraviolet (EUV) light generating apparatus. Here, water soluble gas is used in sensing leakage of cooling water.

0007The present inventive concept also provides a liquid leakage sensing method, which can prevent a collector mirror from being contaminated by sensing leakage of cooling water supplied to the collector mirror of an extreme ultraviolet (EUV) light generating apparatus.

0008These and other objects of the present inventive concept will be described in or be apparent from the following description of the preferred embodiments.

0009According to an aspect of the present inventive concept, there is provided a liquid leakage sensing apparatus including a collector mirror module, a cooling unit configured to supply cooling water to one surface of the collector mirror module, a gas supply unit configured to supply a water soluble gas to the cooling unit, and a sensing unit configured to sense the water soluble gas having leaked to the outside of the cooling unit.

0010According to another aspect of the present inventive concept, there is provided a liquid leakage sensing apparatus including a vessel, a light source configured to supply a light to the vessel, a droplet generator configured to generate a droplet using the light supplied to the vessel, a collector mirror disposed in the vessel and configured to collect and reflect EUV light generated by a reaction between the light and the droplet, a cooling unit disposed at one side of the collector mirror and configured to supply cooling water to one surface of the collector mirror to adjust a temperature of the collector mirror, a gas supply unit supplying a water soluble gas to the cooling unit, and a sensing unit sensing whether the water soluble gas having leaked to the outside of the cooling unit exists in the vessel or not.

0011According to still another aspect of the present inventive concept, there is provided a liquid leakage sensing apparatus including an object, a liquid supply unit configured to supply a process liquid to a liquid receiving space formed in contact with one surface of the object, a gas supply unit configured to supply a water soluble gas to the liquid supply unit, and a sensing unit configured to sense the water soluble gas having leaked to the outside of the liquid receiving space.

0012According to a further aspect of the present inventive concept, there is provided a liquid leakage sensing apparatus including a vessel in which light reacts with a droplet to generate EUV light, a cooling unit configured to supply cooling water to the inside of the vessel, a gas supply unit configured to supply a water soluble gas to the cooling unit, and a sensing unit configured to sense whether the water soluble gas having leaked to the outside of the cooling unit exists in the vessel or not.

0013According to yet another aspect of the present inventive concept, there is provided a liquid leakage sensing method including providing cooling water including a water soluble gas to an object in a vessel, and sensing whether the water soluble gas having leaked to the outside of the object exists in the vessel or not, wherein the sensing comprises measuring a partial pressure of the water soluble gas.

BRIEF DESCRIPTION OF THE DRAWINGS

0014The above and other features and advantages of the present inventive concept will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which:

0015<figref idref="DRAWINGS">FIG. 1</figref> schematically illustrates an extreme ultraviolet (EUV) light generating apparatus;

0016<figref idref="DRAWINGS">FIG. 2</figref> schematically illustrates a liquid leakage sensing apparatus according to an embodiment of the present inventive concept;

0017<figref idref="DRAWINGS">FIG. 3</figref> is a block diagram of the liquid leakage sensing apparatus shown in <figref idref="DRAWINGS">FIG. 2</figref>;

0018<figref idref="DRAWINGS">FIG. 4</figref> illustrates operations of the liquid leakage sensing apparatus shown in <figref idref="DRAWINGS">FIG. 2</figref>;

0019<figref idref="DRAWINGS">FIG. 5</figref> is a block diagram of a liquid leakage sensing apparatus according to another embodiment of the present inventive concept;

0020<figref idref="DRAWINGS">FIG. 6</figref> schematically illustrates the exemplary apparatus shown in <figref idref="DRAWINGS">FIG. 5</figref>;

0021<figref idref="DRAWINGS">FIG. 7</figref> is a schematic block diagram of a liquid leakage sensing apparatus according to still another embodiment of the present inventive concept;

0022<figref idref="DRAWINGS">FIG. 8</figref> is a schematic block diagram illustrating internal circuits of a vessel shown in <figref idref="DRAWINGS">FIG. 7</figref>;

0023<figref idref="DRAWINGS">FIG. 9</figref> is a schematic diagram of a liquid leakage sensing apparatus according to still another embodiment of the present inventive concept;

0024<figref idref="DRAWINGS">FIG. 10</figref> is a schematic block diagram a liquid leakage sensing apparatus according to still another embodiment of the present inventive concept;

0025<figref idref="DRAWINGS">FIG. 11</figref> is a flowchart sequentially illustrating a liquid leakage sensing method according to an embodiment of the present inventive concept;

0026<figref idref="DRAWINGS">FIG. 12</figref> is a flowchart sequentially illustrating a liquid leakage sensing method according to another embodiment of the present inventive concept;

0027<figref idref="DRAWINGS">FIG. 13</figref> is a block diagram of an electronic system including a semiconductor device manufactured using a lithography apparatus according to the present inventive concept; and

0028<figref idref="DRAWINGS">FIGS. 14 and 15</figref> illustrate exemplary semiconductor systems to which a semiconductor device manufactured using a lithography apparatus according to the present inventive concept can be applied.

DETAILED DESCRIPTION OF THE EMBODIMENTS

0029The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The same reference numbers indicate the same components throughout the specification. In the attached figures, the thickness of layers and regions is exaggerated for clarity.

0030It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

0031Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

0032The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted.

0033Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It is noted that the use of any and all examples, or exemplary terms provided herein is intended merely to better illuminate the invention and is not a limitation on the scope of the invention unless otherwise specified. Further, unless defined otherwise, all terms defined in generally used dictionaries may not be overly interpreted.

0034The present invention will be described with reference to perspective views, cross-sectional views, and/or plan views, in which preferred embodiments of the invention are shown. Thus, the profile of an exemplary view may be modified according to manufacturing techniques and/or allowances. That is, the embodiments of the invention are not intended to limit the scope of the present invention but cover all changes and modifications that can be caused due to a change in manufacturing process. Thus, regions shown in the drawings are illustrated in schematic form and the shapes of the regions are presented simply by way of illustration and not as a limitation.

0035Hereinafter, exemplary embodiments in accordance with principles of inventive concepts will be explained in detail with reference to the accompanying drawings.

0036First, an extreme ultraviolet (EUV) light generating apparatus will be described with reference to <figref idref="DRAWINGS">FIG. 1</figref>.

0037<figref idref="DRAWINGS">FIG. 1</figref> schematically illustrates an extreme ultraviolet (EUV) light generating apparatus.

0038Referring to <figref idref="DRAWINGS">FIG. 1</figref>, EUV light is generated using a chemical reaction taking place in the vessel <b>11</b>. A droplet generator <b>31</b> providing a droplet d and a droplet catcher <b>41</b> vertically spaced apart from the droplet generator <b>31</b> and receiving the droplet d are disposed in the vessel <b>11</b>.

0039The droplet d may include at least one of tin (Sn), lithium (Li), and xenon (Xe). In detail, the droplet d may be a gas such as tin (Sn), lithium (Li), or xenon (Xe), or a cluster of gases. The droplet d is preferably provided in a vacuum environment. For example, the vacuum environment in which the drop d is provided is preferably about 1 mbar.

0040The light source <b>21</b> provides first light. That is to say, the first light supplied from the light source <b>21</b> interacts with the droplet d and generates EUV light. The first light supplied from the light source <b>21</b> may be supplied to the droplet d in the vessel <b>11</b> along reflecting mirrors <b>61</b> and <b>62</b>. The first light may be generated by, for example, a CO₂laser. In particular, the first light may be CO₂laser light having a high pulse of 40 kHz or greater and oscillating with a wavelength of 9.3 μm or 10.6 μm.

0041A collector mirror <b>100</b> is disposed on one surface of the vessel <b>11</b>. A hole is formed in the center of the collector mirror <b>100</b>, so that the first light supplied from the light source <b>21</b> may be supplied to the inside of the vessel <b>11</b>. The droplet d supplied from the droplet generator <b>31</b> reacts with the first light supplied to the inside of the vessel <b>11</b> to generate EUV light. The collector mirror <b>100</b> collects and reflects the generated EUV light to focus the EUV light on a focusing lens <b>51</b> and to emit the EUV light to the outside of the vessel <b>11</b>. The thus generated EUV light may be used for a lithography apparatus during a lithography process.

0042Here, since the reflectivity of the collector mirror <b>100</b> affects the radiation intensity of emitted EUV light, it is important to maintain the collector mirror <b>100</b> in a clean state. However, after prolonged use of the EUV light generating apparatus, the collector mirror <b>100</b> in the vessel <b>11</b> may be contaminated by droplet deposits. The contaminated collector mirror <b>100</b> may have lowered reflectivity, so that the output of emitted EUV light may also be lowered. According to the present inventive concept, the contamination of the collector mirror <b>100</b> can be sensed at an early stage, thereby continuously preventing the collector mirror <b>100</b> from being contaminated by taking an immediate measure.

0043<figref idref="DRAWINGS">FIG. 2</figref> schematically illustrates a liquid leakage sensing apparatus according to an embodiment of the present inventive concept, <figref idref="DRAWINGS">FIG. 3</figref> is a block diagram of the liquid leakage sensing apparatus shown in <figref idref="DRAWINGS">FIG. 2</figref> and <figref idref="DRAWINGS">FIG. 4</figref> illustrates operations of the liquid leakage sensing apparatus shown in <figref idref="DRAWINGS">FIG. 2</figref>.

0044Referring to <figref idref="DRAWINGS">FIGS. 2 and 3</figref>, the liquid leakage sensing apparatus <b>1</b> according to an embodiment of the present inventive concept includes a vessel <b>10</b>, a light source <b>20</b>, a droplet generator <b>30</b>, a droplet catcher <b>40</b>, a focusing lens <b>50</b>, a collector mirror <b>100</b>, a cooling unit <b>200</b>, a gas supply unit <b>300</b>, and a sensing unit <b>400</b>.

0045The vessel <b>10</b> is a space for receiving devices for generating EUV light. In the vessel <b>10</b>, a droplet d and first light supplied from the light source <b>20</b> react with each other to generate the EUV light. A droplet generator <b>30</b> and a droplet catcher <b>40</b> may be disposed in the vessel <b>10</b> and the collector mirror <b>100</b> may be disposed on a rear surface of the vessel <b>10</b>. The sensing unit <b>400</b> may be disposed on one surface of the vessel <b>10</b> and may analyze kinds and concentrations of gases contained in the internal space of the vessel <b>10</b>. The vessel <b>10</b> may have a generally closed space. However, a hole for light entrance and emission may be formed on one surface of the vessel <b>10</b>.

0046The light source <b>20</b> provides a first light. Here, the light first light may be generated by, for example, a CO₂laser. In particular, the first light may be CO₂laser light having a high pulse of 40 kHz or greater and oscillating with a wavelength of 9.3 μm or 10.6 μm. The first light supplied from the light source <b>20</b> may interact with the droplet d supplied from the droplet generator <b>30</b> to generate EUV light.

0047The droplet generator <b>30</b> provides the droplet d to the inside of the vessel <b>10</b>. For example, the droplet generator <b>30</b> may be disposed on a top surface of the vessel <b>10</b> and may provide the droplet d toward a bottom surface of the vessel <b>10</b>. The droplet catcher <b>40</b> may be disposed on the bottom surface of the vessel <b>10</b> and may receive the droplet d supplied from the droplet generator <b>30</b>. The droplet d supplied to the inside of the vessel <b>10</b> may interact with the first light supplied from the light source <b>20</b> to generate EUV light. Therefore, the droplet d may include at least one of tin (Sn), lithium (Li), and xenon (Xe). In detail, the droplet d may be a gas such as tin (Sn), lithium (Li), or xenon (Xe), or a cluster of gases.

0048A focusing lens <b>50</b> may be disposed within the vessel <b>10</b> to focus the EUV light generated by the interaction of the droplet d and the first light thereon and may emit the EUV light to the outside of the vessel <b>10</b>.

0049The collector mirror <b>100</b> may be disposed on a rear surface of the vessel <b>10</b> and may collect and reflect the EUV light generated by the interaction of the droplet d and the first light. Here, since the EUV light having reached the collector mirror <b>100</b> is reflected back, the collector mirror <b>100</b> may have an increased temperature. Accordingly, the cooling unit <b>200</b> may be disposed on one surface of the collector mirror <b>100</b> to adjust the temperature of the collector mirror <b>100</b>.

0050The cooling unit <b>200</b> supplies cooling water to one surface of the collector mirror <b>100</b>. The cooling water may be supplied to the one surface of the collector mirror <b>100</b> from a storage tank of the cooling unit <b>200</b> disposed outside the vessel <b>10</b> along a cooling line. The cooling water circulates in the cooling unit <b>200</b> and the cooling unit <b>200</b> has a closed space to prevent the cooling water from leaking to the outside. However, there may be a leak probability of the cooling water due to a hardware architecture defect of the cooling unit <b>200</b>. When some of the cooling water is adhered to a reflecting surface of the collector mirror <b>100</b>, droplet deposits may be deposited on the reflecting surface of the collector mirror <b>100</b>.

0051When the droplet deposits are deposited on the reflecting surface of the collector mirror <b>100</b>, reflection efficiency of the collector mirror <b>100</b> may be lowered, resulting in a reduction in the output of the EUV light generating apparatus. If it is possible to sense in advance whether the cooling water has leaked or not, a proper measure can be taken to address the hardware architecture defect of the cooling unit <b>200</b>. However, if it is not possible to sense in advance whether the cooling water has leaked or not, the collector mirror <b>100</b> may be contaminated and a measure to be taken after the collector mirror <b>100</b> is contaminated may increase temporal and economic costs. Further, the conventional sensing device may make it difficult to sense whether cooling water has leaked or not.

0052According to the present inventive concept, a water soluble gas (WSG) is injected into the cooling water, thereby sensing whether the water soluble gas (WSG) exists within the vessel <b>10</b> or not. When the cooling water has leaked, the water soluble gas (WSG) dissolved in the cooling water may exist in a space of the vessel <b>10</b> and leakage of the cooling water can be easily sensed by detecting the water soluble gas (WSG).

0053The gas supply unit <b>300</b> may inject the water soluble gas (WSG) into the cooling unit <b>200</b>. Here, the water soluble gas (WSG) may include, for example, at least one of Kr, He, Ar, and CO₂. The water soluble gas (WSG) injected into the cooling unit <b>200</b> may be a gas that does not react with a process gas (e.g., H₂gas) contained in the vessel <b>10</b>. That is to say, the H₂gas is supplied to one surface of the collector mirror <b>100</b> from the inside of the vessel <b>10</b> and flows along the one surface of the collector mirror <b>100</b> to maintain the collector mirror <b>100</b> in a clean state while preventing droplet deposits from being deposited on a reflection surface of the collector mirror <b>100</b>. In addition, the flow of the H₂gas may increase EUV light generating efficiency.

0054A gas supply control unit <b>310</b> may be installed in the gas supply unit <b>300</b> to adjust an amount of the water soluble gas (WSG) injected into the cooling unit <b>200</b>. It is necessary to inject the water soluble gas (WSG) into the cooling unit <b>200</b> in an appropriately controlled amount so as not to affect the process. Accordingly, the gas supply control unit <b>310</b> may be installed when necessary.

0055The sensing unit <b>400</b> may be disposed on one inner surface of the vessel <b>10</b> and may sense kinds and concentrations of gases contained in the vessel <b>10</b>. In particular, the sensing unit <b>400</b> may measure a partial pressure of the water soluble gas (WSG) having leaked into the vessel <b>10</b>. The sensing unit <b>400</b> may include, for example, a residual gas analyzer (RGA).

0056An operation of the liquid leakage sensing apparatus according to an embodiment of the present inventive concept will be described with reference to <figref idref="DRAWINGS">FIG. 4</figref>. The water soluble gas (WSG) is injected into the cooling unit <b>200</b> by the gas supply unit <b>300</b> and is supplied to one surface of the collector mirror <b>100</b> to adjust a temperature of the collector mirror <b>100</b> in a state in which the water soluble gas (WSG) is dissolved in cooling water contained in the cooling unit <b>200</b>. When a hardware architecture defect is generated in a portion of the cooling unit <b>200</b> (e.g., a cooling line or one surface of the cooling unit <b>200</b> in contact with the collector mirror <b>100</b>), the cooling water may leak and the water soluble gas (WSG) dissolved in the cooling water may exist in the inner space of the vessel <b>10</b>. The sensing unit <b>400</b> may sense existence of the water soluble gas (WSG) having leaked to the outside of the cooling unit <b>200</b>. In particular, the sensing unit <b>400</b> may sense a partial pressure of the water soluble gas (WSG) to sense existence of the water soluble gas (WSG) in the vessel <b>10</b>, thereby sensing leakage of cooling water.

0057Hereinafter, another embodiment to which the operational principle of the liquid leakage sensing apparatus according to the present inventive concept can be applied will be described.

0058<figref idref="DRAWINGS">FIG. 5</figref> is a block diagram of a liquid leakage sensing apparatus according to another embodiment of the present inventive concept and <figref idref="DRAWINGS">FIG. 6</figref> schematically illustrates the exemplary apparatus shown in <figref idref="DRAWINGS">FIG. 5</figref>. For the sake of brevity and convenient explanation, the following description will focus on differences between the liquid leakage sensing apparatuses according to the present and previous embodiments of the present inventive concept.

0059Referring to <figref idref="DRAWINGS">FIG. 5</figref>, the liquid leakage sensing apparatus <b>2</b> according to another embodiment of the present inventive concept includes an object <b>110</b>, a cooling water supply unit <b>210</b>, a gas supply unit <b>300</b>, and a sensing unit <b>400</b>.

0060The object <b>110</b> means an arbitrary device providing cooling water and needed to adjust its temperature. Referring to <figref idref="DRAWINGS">FIG. 6</figref>, for example, cooling water may be supplied to a first focusing lens <b>51</b> and a second focusing lens <b>52</b>. Here, the object <b>110</b> may be the first focusing lens <b>51</b> or the second focusing lens <b>52</b>.

0061The first focusing lens <b>51</b> may focus first light supplied from a light source <b>20</b> and may supply the focused first light to the inside of a vessel <b>10</b> via a collector mirror <b>100</b>. The second focusing lens <b>52</b> may focus EUV light reflected from the collector mirror <b>100</b> and may emit the focused EUV light to the outside of the vessel <b>10</b>.

0062Since the light reaches the first focusing lens <b>51</b> and the second focusing lens <b>52</b>, the first focusing lens <b>51</b> and the second focusing lens <b>52</b> may have increased temperatures. In order to adjust the temperatures of the first focusing lens <b>51</b> and the second focusing lens <b>52</b>, cooling lines may be additionally provided to supply cooling water to the first focusing lens <b>51</b> and the second focusing lens <b>52</b>. Here, a hardware architecture defect may be generated in the cooling line provided to supply cooling water to the first focusing lens <b>51</b> or a hardware architecture defect may be generated in the cooling line provided to supply cooling water to the second focusing lens <b>52</b>.

0063As described above, if there is leakage of the cooling water supplied to the first focusing lens <b>51</b> or to the second focusing lens <b>52</b>, the leakage of the cooling water may affect the collector mirror <b>100</b> due to prolonged use and may cause droplet deposits to be formed on a reflection surface of the collector mirror <b>100</b>. Therefore, water soluble gas (WSG) is injected into the cooling water supply unit <b>210</b> by the gas supply unit <b>300</b> and the water soluble gas (WSG) is dissolved in the cooling water contained in the cooling water supply unit <b>210</b>. When the cooling water is supplied to the first focusing lens <b>51</b> or to the second focusing lens <b>52</b>, existence of the water soluble gas (WSG) is sensed by the sensing unit <b>400</b>, thereby sensing leakage of cooling water. Meanwhile, liquid leakage sensing apparatuses according to some embodiments of the present inventive concept may be applied to not only a cooling water supply device but also a device of sensing leakage of chloric acid or fluoric acid from a chloric acid or fluoric acid supply device using various kinds of gases.

0064The water soluble gas (WSG) may include, for example, at least one of Kr, He, Ar, and CO₂. In particular, the water soluble gas (WSG) injected into the cooling water supply unit <b>210</b> should be a gas that does not react with a process gas (e.g., H₂gas) contained in the vessel <b>10</b>.

0065As described above, the sensing unit <b>400</b> may measure a partial pressure of the water soluble gas (WSG) having leaked into the vessel <b>10</b>. That is to say, the sensing unit <b>400</b> may include, for example, a residual gas analyzer (RGA).

0066<figref idref="DRAWINGS">FIG. 7</figref> is a schematic block diagram of a liquid leakage sensing apparatus according to still another embodiment of the present inventive concept and <figref idref="DRAWINGS">FIG. 8</figref> is a schematic block diagram illustrating internal circuits of a vessel shown in <figref idref="DRAWINGS">FIG. 7</figref>. For the sake of brevity and convenient explanation, the following description will focus on differences between the liquid leakage sensing apparatuses according to the present and previous embodiments of the present inventive concept.

0067Referring to <figref idref="DRAWINGS">FIG. 7</figref>, the liquid leakage sensing apparatus <b>3</b> according to still another embodiment of the present inventive concept includes a vessel <b>10</b>, a cooling water supply unit <b>210</b>, a gas supply unit <b>300</b>, and a sensing unit <b>400</b>.

0068The vessel <b>10</b> is a space for receiving devices for generating EUV light. In the vessel <b>10</b>, a droplet and light react with each other to generate the EUV light. The vessel <b>10</b> may incorporate arbitrary devices. That is to say, the vessel <b>10</b> may include arbitrary devices required for generating light necessary to produce EUV light. The vessel <b>10</b> may have a generally closed space. However, a hole for light entrance and emission may be formed on one surface of the vessel <b>10</b>. The EUV light may be emitted through the hole.

0069<figref idref="DRAWINGS">FIG. 8</figref> illustrates internal circuits of the vessel <b>10</b>. For example, a droplet generator <b>30</b>, a droplet catcher <b>40</b>, and a collector mirror <b>100</b> may be disposed in the vessel <b>10</b>, which has been substantially the same as described above.

0070The cooling water supply unit <b>210</b> supplies cooling water to the inside of a vessel <b>10</b>. The cooling water may be supplied to adjust a temperature of the vessel <b>10</b> itself or to adjust a temperature of an arbitrary device provided in the vessel <b>10</b>.

0071The gas supply unit <b>300</b> supplies water soluble gas (WSG) to the cooling water supply unit <b>210</b>. The cooling water contained in the cooling water supply unit <b>210</b> is dissolved in the water soluble gas (WSG) and the cooling water having the water soluble gas (WSG) dissolved therein may be supplied to the inside of the vessel <b>10</b>.

0072The water soluble gas (WSG) may include, for example, at least one of Kr, He, Ar, and CO₂. In particular, the water soluble gas (WSG) injected into the cooling water supply unit <b>210</b> should be a gas that does not react with a process gas (e.g., H₂gas) contained in the vessel <b>10</b>.

0073As described above, the sensing unit <b>400</b> may measure a partial pressure of the water soluble gas (WSG) having leaked into the vessel <b>10</b>. That is to say, the sensing unit <b>400</b> may include, for example, a residual gas analyzer (RGA).

0074<figref idref="DRAWINGS">FIG. 9</figref> is a schematic diagram of a liquid leakage sensing apparatus according to still another embodiment of the present inventive concept and <figref idref="DRAWINGS">FIG. 10</figref> is a schematic block diagram of a liquid leakage sensing apparatus according to still another embodiment of the present inventive concept. For the sake of brevity and convenient explanation, the following description will focus on differences between the liquid leakage sensing apparatuses according to the present and previous embodiments of the present inventive concept.

0075Referring to <figref idref="DRAWINGS">FIGS. 9 and 10</figref>, the liquid leakage sensing apparatus <b>4</b> according to still another embodiment of the present inventive concept includes a vessel <b>10</b>, a light source <b>20</b>, a droplet generator <b>30</b>, a droplet catcher <b>40</b>, a focusing lens <b>50</b>, a collector mirror <b>100</b>, a cooling unit <b>200</b>, a gas supply unit <b>300</b>, a sensing unit <b>400</b>, and a pressure gauge unit <b>500</b>.

0076Descriptions of the vessel <b>10</b>, the light source <b>20</b>, the droplet generator <b>30</b>, the droplet catcher <b>40</b>, the focusing lens <b>50</b>, the collector mirror <b>100</b>, the cooling unit <b>200</b>, the gas supply unit <b>300</b>, and the sensing unit <b>400</b> are substantially the same as those of the liquid leakage sensing apparatus <b>1</b> according to previously described embodiments of the present inventive concept.

0077The pressure gauge unit <b>500</b> may measure a pressure change in the vessel <b>10</b>. When cooling water has leaked from the cooling unit <b>200</b>, the water soluble gas (WSG) dissolved in the cooling water is supplied to the vessel <b>10</b> and the pressure gauge unit <b>500</b> measures a pressure of gases in the vessel <b>10</b> including the water soluble gas (WSG), thereby sensing leakage of cooling water.

0078The leakage of cooling water may be sensed by the sensing unit <b>400</b> and the pressure gauge unit <b>500</b> or may be sensed independently using the sensing unit <b>400</b> or the pressure gauge unit <b>500</b>.

0079Hereinafter, liquid leakage sensing methods according to some embodiments of the present inventive concept will be described.

0080<figref idref="DRAWINGS">FIG. 11</figref> is a flowchart sequentially illustrating a liquid leakage sensing method according to an embodiment of the present inventive concept.

0081Referring to <figref idref="DRAWINGS">FIG. 11</figref>, first, the liquid leakage sensing method according to an embodiment of the present inventive concept includes supplying cooling water having a water soluble gas dissolved therein to an object in a vessel (S<b>100</b>). Here, the object may include, for example, a collector mirror or a focusing lens incorporated in the vessel.

0082Next, the water soluble gas dissolved in the cooling water leaks to the outside of the object to sense whether the water soluble gas having leaked to the outside of the object exists in the vessel or not (S<b>110</b>).

0083When the cooling water has leaked to the outside of the object, it is determined that water soluble gas exists in the vessel and leakage of cooling water can be sensed by sensing the water soluble gas existing in the vessel. The water soluble gas may include, for example, at least one of Kr, He, Ar, and CO₂. The water soluble gas (WSG) injected into the cooling unit <b>200</b> may be a gas that does not react with a process gas (e.g., H₂gas) contained in the vessel <b>10</b>.

0084Here, the leakage of cooling water can be sensed by measuring a partial pressure of the water soluble gas dissolved in the cooling water in the vessel.

0085<figref idref="DRAWINGS">FIG. 12</figref> is a flowchart sequentially illustrating a liquid leakage sensing method according to another embodiment of the present inventive concept.

0086Referring to <figref idref="DRAWINGS">FIG. 12</figref>, the liquid leakage sensing method according to another embodiment of the present inventive concept includes supplying cooling water including a water soluble gas to an object in a vessel (S<b>100</b>) and sensing whether the water soluble gas having leaked to the outside of the object exists in the vessel or not (S<b>110</b>).

0087Additionally, a pressure change in the vessel is measured to determine whether there is leakage of cooling water (S<b>120</b>).

0088When the cooling water has leaked to the outside of the object, it is determined that the water soluble gas exists in the vessel, and the pressure in the vessel may increase. Therefore, the leakage of cooling water can be determined by measuring the pressure change in the vessel.

0089<figref idref="DRAWINGS">FIG. 13</figref> is a block diagram of an electronic system including a semiconductor device manufactured using a lithography apparatus according to the present inventive concept.

0090Referring to <figref idref="DRAWINGS">FIG. 13</figref>, the electronic system <b>4100</b> according to an embodiment of the present inventive concept may include a controller <b>4110</b>, an input/output device (I/O) <b>4120</b>, a memory device <b>4130</b>, an interface <b>4140</b> and a bus <b>4150</b>.

0091The controller <b>4110</b>, the I/O <b>4120</b>, the memory device <b>4130</b> and/or the interface <b>4140</b> may be connected to each other through the bus <b>4150</b>. The bus <b>4150</b> corresponds to a path through which data move.

0092The controller <b>4110</b> may include at least one of a microprocessor, a digital signal processor, a microcontroller, and logic elements capable of functions similar to those of these elements.

0093The I/O <b>4120</b> may include at least one selected from a keypad, a keyboard, a display device, and so on.

0094The memory device <b>4130</b> may store data and/or codes.

0095The interface <b>4140</b> may perform functions of transmitting data to a communication network or receiving data from the communication network. The interface <b>4140</b> may be wired or wireless. For example, the interface <b>4140</b> may include an antenna or a wired/wireless transceiver, and so on.

0096Although not shown, the electronic system <b>4100</b> may further include high-speed DRAM and/or SRAM as a working memory for improving the operation of the controller <b>4110</b>. The semiconductor devices using a mask for photolithography according to the embodiments of the present inventive concept may be provided in the memory device <b>4130</b> or may be provided as some components of the controller <b>4110</b> or the I/O <b>4120</b>.

0097The electronic system <b>4100</b> may be applied to a personal digital assistant (PDA), a portable computer, a web tablet, a wireless phone, a mobile phone, a digital music player, a memory card, or any type of electronic device capable of transmitting and/or receiving information in a wireless environment.

0098<figref idref="DRAWINGS">FIGS. 14 and 15</figref> illustrate exemplary semiconductor systems to which a semiconductor device manufactured using a lithography apparatus according to the present inventive concept can be applied.

0099<figref idref="DRAWINGS">FIG. 14</figref> illustrates an example in which a semiconductor device according to an embodiment of the present inventive concept is applied to a tablet PC and <figref idref="DRAWINGS">FIG. 15</figref> illustrates an example in which a semiconductor device according to an embodiment of the present inventive concept is applied to a notebook computer. One skilled in the art would understand that semiconductor devices according to some embodiments of the present inventive concept may also be applied to other IC devices not illustrated herein.

0100While the present inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present inventive concept as defined by the following claims. It is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than the foregoing description to indicate the scope of the inventive concept.